Fine needle aspiration and the Bethesda system: Correlation with histopathology in 1,228 surgical patients

Fine-needle aspiration combined with the Bethesda System for Reporting Thyroid Cytopathology is indispensable in the diagnostic evaluation of thyroid nodules. Their increased detection over the last few decades mandates the determination of which thyroid nodules require surgical management for malignancy. This study examines the correlation of fine-needle aspiration to final histopathology of dominant thyroid nodules in a large series of surgical patients undergoing thyroidectomy at a single academic institution.

A retrospective review of prospectively collected data of 1,228 patients who underwent fine-needle aspiration for a dominant thyroid nodule and thyroidectomy from a single institution between 2010 and 2019 was performed. The cases were stratified into all 6 Bethesda categories. Fine-needle aspiration results were compared to index thyroid nodule malignancy on final histopathology.

Of 1,228 patients who underwent thyroidectomy, the overall malignancy rate was 53%. When fine-needle aspiration was stratified by the Bethesda System for Reporting Thyroid Cytopathology, malignancy rate was 29% for nondiagnostic; 11% for benign; 51% for atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS); 47% for follicular neoplasm/suspicious for follicular neoplasm (FN/SFN); 84% for suspicious for malignancy (SFM); and 98% for malignant results on final histopathology. There was a false positive rate of 1% and false negative rate ranging from 7 to 11%.

Fine-needle aspiration of a dominant thyroid nodule in patients who underwent thyroidectomy had an overall malignancy rate of 53%. False negative and false positive rates are within the reported range in surgical patient populations. The majority of patients with AUS/FLUS, FN/SFN and SFM results with underlying malignancy received the appropriate surgical resection.